I'm betting my money on tension, my friend. When we're anxious or stressed we unconsciously tense up all around. In fact sometimes I have to remind myself to loosen up my shoulders (they'll be practically to my ears!)
You could also be tensing your jaw, which can also cause pain in or around the face. Mix all that with some possible sinus flare up from allergies, then there ya go. :)
Regarding brain tumors, that's one of those things you don't really sit around and question if you have or not. The symptoms are pretty extreme and interfere with daily life to the point where you're like, " Whoa, I need to see a doctor ASAP." I.e seizures, EXTREME dizziness etc..
So dont worry too much about it, buddy. I'd bet my house and two cats you're alright :)